Highly reflective and high-Q thin resonant subwavelength gratings

Abstract We theoretically investigate the design of thin subwavelength gratings possessing high-reflectivity and high- Q resonances when illuminated at normal incidence by a Gaussian beam. We compare the performances of single-period and dual-period rectangular gratings using finite element method-based optimization and predict a close to two orders of magnitude improvement (×90) in their transmission loss-linewidth product, which is the relevant figure of merit for e.g. resonant mirror-based microcavity applications.